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@xkrebstarx avatar
UTC

Molto Verboso
1966 Bluebadge, 1974 Super 150
Joined: UTC
Posts: 1117
Location: New York City
 
Molto Verboso
@xkrebstarx avatar
1966 Bluebadge, 1974 Super 150
Joined: UTC
Posts: 1117
Location: New York City
UTC quote
Hey guys,

I'm a noob doing a partial restore on a 125cc Blue Badge. The body is largely rust free, but I hit some deep rust under the gas tank. What's the proper fix for something like this...

External inline image provided by member with no explanatory text

Cut and weld? Rust converter? Keep-on sanding? Other ideas?

There's about a 4in by 4in patch like this photo. It does touch the front of the rear suspension mount. Also, the metal looks good from the engine side.

If it helps, here's a link to a larger photo...

http://coparoom.com/pics_public/rust.jpg

I do realize that this type of thread has been done to death, but I wanted to get a little deeper into the theory. I.e. when is rust "too much rust".
@rob98801 avatar
UTC

Addicted
85 Vespa PX150E with sidecar, 80 P200 with sidecar, 96 Goldwing with Hannigan Sidecar, LR87aj5, LR91aj3
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Location: Central Washington State
 
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@rob98801 avatar
85 Vespa PX150E with sidecar, 80 P200 with sidecar, 96 Goldwing with Hannigan Sidecar, LR87aj5, LR91aj3
Joined: UTC
Posts: 580
Location: Central Washington State
UTC quote
The ideal fix? Deep pockets. Sorry I just had to get that in.

I am going to assume that a sharp pointed awl would break thru at some of the places I see in the picture.

If I were doing this I would Cut and weld in metal where needed then have the frame media blasted, treated with a rust killer and then primed with a epoxy based primer (DP40). The end product will depend on your skill level, available tools and of course the patience to finish the job.

YMMV
OP
@xkrebstarx avatar
UTC

Molto Verboso
1966 Bluebadge, 1974 Super 150
Joined: UTC
Posts: 1117
Location: New York City
 
Molto Verboso
@xkrebstarx avatar
1966 Bluebadge, 1974 Super 150
Joined: UTC
Posts: 1117
Location: New York City
UTC quote
Thanks for the reply, YMMV.

I knew this project wouldn't be cheap, so I'm cool with spending a few bucks. Learning how to do the work is more important to me than the final product.
I'll worry about finish on the next project.

To give you a point of reference, I've managed to remove most of the cowl dents, floorboard waves, and legshield bends through trial-and-error, watching Restolad and such. Also, did a complete disassembly of the bike using the Darnell and Golfen book. Luckily, I had enough foresight to buy a project with a running engine. So, this rust is really my last scary hurdle to having a decent ride.
Quote:
I am going to assume that a sharp pointed awl would break thru at some of the places I see in the picture.
Would an awl be a good litmus test? That is, if the awl doesn't poke though and the steel has some thickness left, then it's okay structurally. Or, should I be overly pessimistic about it and cut-and-weld regardless?
Quote:
If I were doing this I would Cut and weld in metal where needed then have the frame media blasted, treated with a rust killer and then primed with a epoxy based primer (DP40). The end product will depend on your skill level, available tools and of course the patience to finish the job.


Tools I have... welder, grinder, dremel, you name it (Thanks, Dad). I do not have skillz though. I've taken a basic welding/metal shaping class, but that's it. I figured this would be a good real-world learning experience.

My current plan is to stitch weld using a 1mm thick steel patch. I am also planning to MIG weld (Lincoln 135 / Maybe using shielding gas?). I'm not sure what type of wire to use though... I've been told that a thin brass wire is the right choice. Does this all sound reasonable?
@rob98801 avatar
UTC

Addicted
85 Vespa PX150E with sidecar, 80 P200 with sidecar, 96 Goldwing with Hannigan Sidecar, LR87aj5, LR91aj3
Joined: UTC
Posts: 580
Location: Central Washington State
 
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@rob98801 avatar
85 Vespa PX150E with sidecar, 80 P200 with sidecar, 96 Goldwing with Hannigan Sidecar, LR87aj5, LR91aj3
Joined: UTC
Posts: 580
Location: Central Washington State
UTC quote
Y.M.M.V. Your Mileage May Vary

Meaning my way is not the only way so your results may be different.


I think you have a realistic plan in place ie. this next one will be better.


I'm not sure if the awl is the last authority but I trust it to find the worst of the worst, if there are really no points of "thru an thru" rusted areas, if its not in a strength required area, I have been known to apply a double coat of rust killer and then coat with a layer of fiber glass body filler (not "bondo"). Sand and finish off as usual. If there even the smallest pin hole moisture will get in behind the "bondo" so great care must be used to seal the surface otherwise the finish will not last thus the need to use a fiber glass type filler.


Rob
OP
@xkrebstarx avatar
UTC

Molto Verboso
1966 Bluebadge, 1974 Super 150
Joined: UTC
Posts: 1117
Location: New York City
 
Molto Verboso
@xkrebstarx avatar
1966 Bluebadge, 1974 Super 150
Joined: UTC
Posts: 1117
Location: New York City
UTC quote
Rob98801 wrote:
Y.M.M.V. Your Mileage May Vary
Quote:
I think you have a realistic plan in place ie. this next one will be better.


I'm not sure if the awl is the last authority but I trust it to find the worst of the worst, if there are really no points of "thru an thru" rusted areas, if its not in a strength required area, I have been known to apply a double coat of rust killer and then coat with a layer of fiber glass body filler (not "bondo"). Sand and finish off as usual. If there even the smallest pin hole moisture will get in behind the "bondo" so great care must be used to seal the surface otherwise the finish will not last thus the need to use a fiber glass type filler.


Rob
Awesome. Thanks again for the info, Rob.

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